https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120588
Bug ID: 120588
Summary: [14/15/16 regression] poor code when returning struct
Product: gcc
Version: 14.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: ell_se at yahoo dot com
Target Milestone: ---
The following code:
struct X {
int i;
long l;
};
struct X f (struct X x) {
return x;
}
Compiled with -O2 on x86-64:
f:
mov rax, rsi
mov rsi, rdi
push rbp
pop rbp
mov rdi, rax
mov rax, rsi
mov rdx, rdi
ret
Testing on godbolt, this started with GCC 14.1 and up to trunk. GCC 13.3
produces the expected:
f:
mov rdx, rsi
mov eax, edi
ret
Other variants of this also produce worse code than 13.3, but that's the most
obvious example.
